#include <SFML/Graphics.hpp>
using namespace sf;

const int num = 8; //checkpoints
int points[num][2] = { 300, 610,
					  1270,430,
					  1380,2380,
					  1900,2460,
					  1970,1700,
					  2550,1680,
					  2560,3150,
					  500, 3300 };

struct Car
{
	float x, y, speed, angle; int n;

	Car() { speed = 2; angle = 0; n = 0; }

	void move()
	{
		x += sin(angle) * speed;
		y -= cos(angle) * speed;
	}

	void findTarget()
	{
		float tx = points[n][0];
		float ty = points[n][1];
		float beta = angle - atan2(tx - x, -ty + y);
		if (sin(beta) < 0) angle += 0.005*speed; else angle -= 0.005*speed;
		if ((x - tx)*(x - tx) + (y - ty)*(y - ty) < 25 * 25) n = (n + 1) % num;
	}
};


int main()
{
	RenderWindow app(VideoMode(640, 480), "Car Racing Game!");
	app.setFramerateLimit(60);

	Texture t1, t2, t3;
	t1.loadFromFile("images/background.png");
	t2.loadFromFile("images/car.png");
	t1.setSmooth(true);
	t2.setSmooth(true);

	Sprite sBackground(t1), sCar(t2);
	sBackground.scale(2, 2);

	sCar.setOrigin(22, 22);
	float R = 22;

	const int N = 5;
	Car car[N];
	for (int i = 0; i < N; i++)
	{
		car[i].x = 300 + i * 50;
		car[i].y = 1700 + i * 80;
		car[i].speed = 7 + i;
	}

	float speed = 0, angle = 0;
	float maxSpeed = 12.0;
	float acc = 0.2, dec = 0.3;
	float turnSpeed = 0.08;

	int offsetX = 0, offsetY = 0;

	while (app.isOpen())
	{
		Event e;
		while (app.pollEvent(e))
		{
			if (e.type == Event::Closed)
				app.close();
		}

		bool Up = 0, Right = 0, Down = 0, Left = 0;
		if (Keyboard::isKeyPressed(Keyboard::Up)) Up = 1;
		if (Keyboard::isKeyPressed(Keyboard::Right)) Right = 1;
		if (Keyboard::isKeyPressed(Keyboard::Down)) Down = 1;
		if (Keyboard::isKeyPressed(Keyboard::Left)) Left = 1;

		//car movement
		if (Up && speed < maxSpeed)
			if (speed < 0)  speed += dec;
			else  speed += acc;

		if (Down && speed > -maxSpeed)
			if (speed > 0) speed -= dec;
			else  speed -= acc;

		if (!Up && !Down)
			if (speed - dec > 0) speed -= dec;
			else if (speed + dec < 0) speed += dec;
			else speed = 0;

		if (Right && speed != 0)  angle += turnSpeed * speed / maxSpeed;
		if (Left && speed != 0)   angle -= turnSpeed * speed / maxSpeed;

		car[0].speed = speed;
		car[0].angle = angle;

		for (int i = 0; i < N; i++) car[i].move();
		for (int i = 1; i < N; i++) car[i].findTarget();

		//collision
		for (int i = 0; i < N; i++)
			for (int j = 0; j < N; j++)
			{
				int dx = 0, dy = 0;
				while (dx*dx + dy * dy < 4 * R*R)
				{
					car[i].x += dx / 10.0;
					car[i].x += dy / 10.0;
					car[j].x -= dx / 10.0;
					car[j].y -= dy / 10.0;
					dx = car[i].x - car[j].x;
					dy = car[i].y - car[j].y;
					if (!dx && !dy) break;
				}
			}


		app.clear(Color::White);

		if (car[0].x > 320) offsetX = car[0].x - 320;
		if (car[0].y > 240) offsetY = car[0].y - 240;

		sBackground.setPosition(-offsetX, -offsetY);
		app.draw(sBackground);

		Color colors[10] = { Color::Red, Color::Green, Color::Magenta, Color::Blue, Color::White };

		for (int i = 0; i < N; i++)
		{
			sCar.setPosition(car[i].x - offsetX, car[i].y - offsetY);
			sCar.setRotation(car[i].angle * 180 / 3.141593);
			sCar.setColor(colors[i]);
			app.draw(sCar);
		}

		app.display();
	}

	return 0;
}
